Ion beam implanters are widely used in the process of doping of semiconductor wafers with a desired species of ions. An ion beam implanter generates an ion beam comprises of the desired species of ions. The ion beam impinges upon an exposed surface of a semiconductor wafer workpiece thereby “doping” or implanting the workpiece surface with desired ions. Some ion beam implanters utilize serial implantation wherein a single semiconductor wafer workpiece is positioned on a support in an implantation chamber. The support is oriented such that the workpiece is in the ion beam beam-line and the ion beam is repetitively scanned over the workpiece to implant a desired dosage of ions. When implantation is complete, the workpiece is removed from the support and another workpiece is positioned on the support.
In U.S. Pat. No. 6,137,112, a high-energy ion beam implanter is disclosed as that shown in FIG. 1. The implanter 10 produces an ion beam 14 having beam energy in the range of 10-5000 kilo-electron volts (keV). The implanter 10 includes an ion source 12 for providing ions that form the ion beam 14 which traverses a beam path to an implantation or end station 16. The implanter 10 utilizes a radio frequency (RF) ion accelerator 18 to accelerate ions in the ion beam 14 to suitably high velocities to achieve the desired ion beam energy. A suitable RF ion accelerator 18 for use in a high energy implanter is disclosed in U.S. Pat. No. 4,667,111 to Glavish et al.
The high energy ion beam implanter uses a rotating, translating disk-shaped support on which workpieces are mounted. A plurality of semiconductor workpieces are mounted on the disk-shaped support. The support is supported in an implantation chamber of an end or implantation station of the ion beam implanter. The rotation and translation of the support allows each of the plurality of workpieces to be exposed to the ion beam during a production run with reliable and accurate dose control and large ion beam thermal power dissipation because the power can be evenly irradiated on several wafers.
However, as the wafer size increases from 200 to 300 mm in semiconductor chip manufacturing, users have been adopting a concept or processing a wafer at time, which is called serial implantation wherein a single semiconductor wafer workpiece is positioned on a support in an implantation chamber. The support is oriented such that the workpiece is in the ion beam line and the ion beam is repetitively scanned over the workpiece to implant a desired dosage of ions. When implantation is complete, the workpiece is removed from the support and another workpiece is positioned on the support. This serial implantation concept is widely used in medium dose implantation apparatus. A medium current ion implanter as shown in FIG. 2B of U.S. Pat. No. 6,777,696 has the following sub-systems.
FIG. 2 illustrates an ion implantation system 262 suitable for medium current ion implants. The system 262 includes an ion source 282, wherein the gas(es) can be ionized to generate ions suitable for implantation into wafers or workpieces. An ion beam extraction assembly 276 is included to extract ions from the ion source 282 and accelerate them into a beamline 278, which includes a mass analysis magnet 280. The mass analysis magnet 280 is operable to sort out or reject ions of an inappropriate charge-to-mass ratio. In order to obtain uniform implants over workpieces ion beam scanning component 270 and a component 284 must be included in a serial implanter system. The beam collimator 284 is to control the angle of the scanned ion beam. An acceleration/deceleration column 286 facilitates controlling and adjusting the ion beam energy. A component 288 may be included to filter out contaminant particles, such as a final energy. Wafers or workpieces 290 are loaded into an end station chamber 292 for selective implantation with ions. A mechanical scan drive 294 maneuvers the wafers within the chamber 292 to facilitate selective encounters with the beam(s). The wafers or workpieces 290 are moved into the end station chamber 292 by a wafer handling system 296, which may include, for example, one or more mechanical or robotic arms 297.
Conventionally, medium and high energy ion implanters are two very different types of implanters as shown FIG. 1 and FIG. 2. The implanter manufacturers release two total different designs. It would add costs on manufacturing and complexity for the users to operate the systems. To combine the two machines into one system is possible in a serial implantation system.
On the other hand, high energy ion implanters use RF electrical fields to accelerate ions to 10 to 5000 kilo-electron volts (keV). However, there is a set of optimal ion velocity values in a particularly designed RF linear accelerator (LINAC). In ion implantation applications, wide ranges of ion energy (10-4,000 keV) and different species ions (boron, silicon, phosphorus, and arsenic are commonly used) so that the sets of ion velocities in LINAC can be over one hundred. The RF LINAC high energy ion implanters were designed with many resonator cavities to compensate these velocity unmatched values. But the cavity number can be too large because of its costs and space limitations. Therefore, imperfect velocity matches inside LINAC are resulted, consequently, poor ion transmissions through LINAC and degradations of LINAC components (due to un-transmitted ion bombardments are observed.